Here is an article which explains why we prepare for Sukkot as soon as Yom Kippur ends...
http://www.torah.org/learning/integrity/fiveDaysYomKippur.htmlPriceless Integrity
The Five Days of Yom KippurDays of AtonementThere was once a province of a large kingdom that owed an enormous amount of money in taxes to the sovereign. Upset by the laxity of his subjects in paying their debts, the king decided that the time had come to take action. He summoned his armed forces, and together they traveled to the province in order to collect the overdue tariff.
As the king approached, the leaders of the province came out to greet him. They implored their monarch to have pity on them, as they were poverty-stricken and had nothing to give him. Touched by their words, the king reduced their debt by a third. As the king's retinue advanced closer to the province, the important members of the community came out to receive him. As they repeated the words of the leaders, the king decided to reduce the debt by another third. When the king finally arrived in the province, all the common folk came out to humble themselves before him. Moved by all that had transpired, he canceled the debt entirely.
Our Sages present this story as a parable to the time before and after the ten days of repentance. The residents of the province are the Jewish people; the debt is the year's accumulation of sins. On erev Rosh HaShanah the extremely righteous take the first step toward appeasing HaShem by fasting, and in response, HaShem pardons a third of our sins. During the Aseres Yemei Teshuvah, the important members of the community fast, and another third is removed. Finally, on Yom Kippur, everyone refrains from food, and HaShem erases all of our transgressions.
During the four days between Yom Kippur and Sukkos, the Jewish people are so involved with building their sukkos and buying their lulav and esrog, that they are too busy to sin. Therefore Sukkos is refered to as "The First Day," for only then does the new record of transgressions begin (Medrash as cited by Tur 581).Is it in fact possible for every member of the Jewish people to pass through these four days without a single aveirah? Especially when caught up with the hustle and bustle of purchasing a lulav and esrog and building a sukkah, one could very easily stumble and commit a transgression such as damaging merchandise or disturbing the neighbors at night.
From the words of Chazal, it is clear that even if a Jew commits a sin during these days, HaShem immediately forgives it. Our Sages reveal to us that Yom Kippur does not end after Ne'ilah, but actually continues for a total of five days - until the start of the Yom Tov of Sukkos (Biyur HaGra 524: 5). How can we understand this?
After much pleading for forgiveness from his loved one, a person will usually agree to overlook the other's misdeeds. Yet we all know that this concession does not mean that the closeness the two once shared has been fully restored. Only if the wrongdoer makes special efforts to show his love for the offended party can he hope to regain that affection.
Yom Kippur and the days that precede it are days of repentance characterized by fear and awe. During this time, the Jewish people fast in order to demonstrate their sincere regret over their transgressions of the previous year. The four days following Yom Kippur are also days of repentance, but now we are in a totally different emotional state. Complete involvement with the mitzvos of sukkah and dalet minim, the four species, shows our tremendous devotion to our beloved King. HaShem responds by extending the atonement that began during Yom Kippur (Shlah HaKodesh, Maseches Sukkah, 193b ).
Rising UpAfter a whole day of fasting and prayer, we can understand that someone would want to "take a break" before engaging in a new endeavor. The halachah cautions us against such a response, directing those who are scrupulous about their mitzvah observance to start building the sukkah immediately (Rema 624: 5). By beginning with the mitzvah of sukkah as soon as we have finished the avodah of Yom Kippur, we actualize King David's words: "They go from strength to strength" (Tehillim 84: 8).
The poskim mention the option of learning the Gemara or the halachos of Sukkos as a substitute for actually starting to build the sukkah (Aruch HaShulchan 624: 7). Alternatively, one can discuss these topics with his family members (Kaf HaChaim 624: 35). Once, after an extremely fervent Yom Kippur in the company of the Vilna Gaon, one of the Gaon's students inquired as to when they would be putting up the "first stake" of the sukkah. The Gaon took out a volume of Maseches Sukkah and started to learn with him. Toward the end of the night, when they had completed the entire tractate, the Gra commented: "I think we managed to get a "stake" in the sukkah" (Rav Shlomo Brevda).Even if a person decides to learn the halachos of sukkah right after Yom Kippur, he should not put off building the sukkah more than one night. Even if the day after Yom Kippur is erev Shabbos, he should get up early to complete his sukkah (Mishnah Berurah 625: 2).
With all the mitzvos that we must attend to after Yom Kippur, one would think that it would be a good idea to get a head start by building the sukkah beforehand. Although this might sound very practical, Chazal advise us against doing so. In the event that we have been sentenced by HaShem to receive the punishment of galus, exile, we can fulfill this punishment through building the sukkah (Elya Rabbah 624). Some maintain that since the principal act of building the sukkah is the placement of the schach - so as long as one saves this job for after Yom Kippur, he may build the walls of the sukkah beforehand (Birkei Yosef).
Torah Honor"After a person has been appointed dayan of the community, it is forbidden for him to perform manual labor in front of three people" (Kiddushin 70a according to Yam Shel Shlomo 4: 4; Choshen Mishpat 8: 4). In view of this teaching, may a dayan construct a sukkah? Since there is no greater honor than involving oneself with HaShem's commandments, even the greatest talmid chacham may build a sukkah in front of others (Sha'arei Teshuvah 625).
One year Yom Kippur fell on a Thursday, and on erev Shabbos the Maharil went to visit his teacher, the Marharam. Although the Maharil was one of the Maharam's closest disciples, since the Maharam was engaged in building his sukkah he did not have time to talk to his close talmid or to any of the other people who had lined up to consult with him on matters of halachah. Quoting Chazal's injunction, "A mitzvah that comes one's way should not be left to sour" (Mechilta, Parshas Bo), the Maharam put all other considerations aside (Maharil, Hilchos Sukkah p. 50).
Bon Appetit
"Go and eat your bread with joy and drink wine with a good heart, for HaShem is delighted with your actions" (Koheles 9: 7). All year long, a wall of sin separates us from our Father in Heaven. After the conclusion of Yom Kippur, the Jewish people are cleansed of their transgressions and the barrier falls away.
How do we celebrate this joyous occasion? Chazal tell us that after Yom Kippur a Heavenly voice proclaims the words of the above verse, urging us to share HaShem's pleasure through a festive meal. This this seudah following the fast takes on the status of a semi-Yom Tov meal (Tosafos Yeshanim, Yoma 87b).
Does this seudas mitzvah take precedence over building the sukkah? The poskim write that if a person has the strength to do so, he should perform some small act connected with the construction of the sukkah even before he sits down to eat (Kaf HaChaim 624: 36). After the meal, those who are scrupulous in their mitzvah observance should try to continue building the sukkah (Responsa Devar Yehoshua 2: 17).
Mazal Tov"Between Yom Kippur and Sukkos is a time of special joy. We do not say Tachanun and we do not fast, even on the occasion of a parent's yahrtzeit. These days are joyful not only because HaShem does not consider our transgressions during this time, but also because during this period King Solomon completed building the Beis HaMikdash." (Levush 624: 15).Although these days have a festive atmosphere, and marriages may not take place on Yom Tov (with the exception of erev Yom Tov), a chasan and kallah are permitted to get married between Yom Kippur and Sukkos. Aside from the practical difficulties of organizing a wedding during this hectic time, weddings are generally not held on erev Yom Tov since the wedding banquet would continue into the holiday itself, inevitably interfering with the simcha of the mo'ed (Magen Avraham 546: 4).
Do a chasan and kallah fast before their chuppah if they get married during these days? One of the main reasons that a bride and groom refrain from eating on their wedding day is because the wedding day is compared to Yom Kippur. Since the days between Yom Kippur and Sukkos already resemble Yom Kippur in that HaShem does not record one's unintentional transgressions, a chasan and kallah who feel that fasting will weaken them may be lenient with regard to this fast (Mateh Efraim and Elef LeMagen 625: 2).
Days of DevotionOn Yom Kippur, the Jewish people were forgiven for the sin of the golden calf and were given the second set of luchos. Yet even after this tremendous act of pardon, we still did not know if we had found favor in HaShem's eyes.
During the days between Yom Kippur and Sukkos, the Jewish people gave away much of the wealth that they had taken from Egypt, for the sake of building the Mishkan, the tabernacle in the desert. On Sukkos, HaShem responded by showing His intense love for us when He returned the Clouds of Glory (commentary of the Vilna Gaon on Shir HaShirim 1: 4).
Every year from Elul until Yom Kippur, we toil to repair our relationship with our Creator. When Yom Kippur ends, although we are cleansed of our aveiros, our job is not complete.
Between Yom Kippur and Sukkos we engage ourselves completely in mitzvos in order to encourage HaShem to show His deep love for us. Perhaps these four days are the most critical in the entire Jewish calendar, for they determine the true extent of our devotion to HaShem. The intense love that is meant to exist between us cannot return until our actions match up to our prayers.The Chasam Sofer was known for his incredible diligence; he would not squander even a moment of time from his Torah learning. Nevertheless, he wrote an entire book of songs. When his son the, K'sav Sofer, was asked where his father found the time to compose these verses, he replied that during the days between Yom Kippur and Sukkos his father had been so totally overwhelmed with powerful feelings of love toward his Creator that he had difficulty learning Torah. In an attempt to express his deepfelt sentiments, he penned those words (Nachlei Binah, p. 8).
In the merit of our serving HaShem with devotion, may He show His true love to us, His children, and bring us all back to His Home quickly.